Preparing the leather. Before glueing use a patch of rough gauge sandpaper to roughen the smooth side of the gusset and right round the smooth inside edge of the bag to a depth of 1/2". This will give the glue a good key.

Latex Adhesive. Using the right glue is essential. I have always used "Gripsotex" - described as for "bonding low absorbent, close grain leather." It may be available under other brand names. It has the consistency of creamy milk. I just dip my finger in it and immediately rub it right into the leather so that it soaks in well before setting.

Applying the glue. Apply the glue liberally to one side of the gusset and to the 1/2" roughened area right round the inside edge of the bag, (except the neck), and leave until touch dry. I usually apply the glue with my finger, making sure to rub it well in to the leather. It dries to a rubber film within a few minutes and will then very easily peel off your fingers. (Warning: Make very sure you DON'T splash it onto your clothing as I don't know of anything that will get it out once it dries).

Sticking down. Once all the glued areas are touch dry, attach the gusset to one side of the bag. Make very sure that you position the gusset just right the first time. Gripsotex is a very strong contact adhesive and once the two surfaces are brought together they will be very difficult to part again. Start at the back of the bag positioning the end of the gusset right in the crease so that when you come to fold over the top half of the bag, there will be no gap between the end of the gusset and the crease. Work your way round the bottom half of the bag, attaching the gusset so that its outer edge is flush with the edge of the bag.

Apply glue to the top side of the gusset and leave to dry.

Fold over the top half of the bag and lay it flat on top of the gusset, making sure there is no gap between the crease and the end of the welt. Press down lightly to fix it in place.

Hammering down. Lay the bag on a firm, clean, flat surface and firmly hammer the whole glued area on both sides of the bag to force all the glued surfaces together.

Clean up the edge. The edge of the bag should now be three layers of leather with the three edges lying neatly together forming a single smooth surface, ready to take the welt. If it looks at all untidy or uneven, go round the edge of the bag with a sharp craft trimming off any untidy edges.